GitLab CI/CD: Architecting, Deploying, and Optimizing Pipelines
Continuous Integration with GitLab
Docker Push
In this guide, we’ll extend our GitLab CI/CD pipeline by adding a docker_push job that uploads your built image to Docker Hub. By the end, you’ll have a fully automated workflow—from unit tests to containerization and Docker pushes.
1. Existing Pipeline Overview
Here’s the current .gitlab-ci.yml with four jobs: unit_testing, code_coverage, docker_build, and docker_test. We run these on the main branch or any feature/* branch, including merge requests.
name: Solar System NodeJS Pipeline
rules:
- if: $CI_COMMIT_BRANCH == 'main' || $CI_COMMIT_BRANCH =~ /^feature/
when: always
- if: $CI_MERGE_REQUEST_SOURCE_BRANCH_NAME =~ /^feature/ && $CI_PIPELINE_SOURCE == 'merge_request_event'
when: always
stages:
- test
- containerization
variables:
DOCKER_USERNAME: siddharth67
IMAGE_VERSION: $CI_PIPELINE_ID
unit_testing:
# …
code_coverage:
# …
docker_build:
# …
docker_test:
# …
2. Adding the docker_push Job
We’ll append a fifth stage, docker_push, under containerization. This job will:
- Depend on
docker_buildanddocker_testvianeeds - Leverage Docker-in-Docker (
dind) for pushing images - Load the previously saved artifact
- Authenticate to Docker Hub using CI/CD variables
- Push the image tagged with
$IMAGE_VERSION
docker_push:
stage: containerization
needs:
- docker_build
- docker_test
image: docker:24.0.5
services:
- docker:24.0.5-dind
script:
# 1. Load the saved Docker image artifact
- docker load -i image/solar-system-image-$IMAGE_VERSION.tar
# 2. Authenticate with Docker Hub
- docker login --username=$DOCKER_USERNAME --password=$DOCKER_PASSWORD
# 3. Push the image to Docker Hub
- docker push $DOCKER_USERNAME/solar-system:$IMAGE_VERSION
Warning
Ensure your DOCKER_PASSWORD is masked and protected in GitLab. Never hard-code credentials in your .gitlab-ci.yml.
3. Defining CI/CD Variables
Navigate to Settings → CI/CD → Variables in your GitLab project and add:
| Variable Name | Value | Masked | Description |
|---|---|---|---|
| DOCKER_USERNAME | siddharth67 | No | Your Docker Hub username |
| DOCKER_PASSWORD | <your_password> | Yes | Your Docker Hub password or access token |
| M_DB_PASSWORD | <mongodb_pass> | Yes | MongoDB connection password (if needed) |
Note
You can also set pipeline-level variables via the GitLab API or include them in a protected group for reuse across multiple projects.
4. Pipeline Visualization
After pushing the updated .gitlab-ci.yml, GitLab will display five jobs in sequence. The docker_push job runs last, once image build and tests complete.
5. Sample docker_push Logs
Below is an example of a successful Docker push in your CI logs:
$ docker load -i image/solar-system-image-123.tar
Loaded image: solar-system:123
$ docker login --username=siddharth67 --password=$DOCKER_PASSWORD
Login Succeeded
$ docker push siddharth67/solar-system:123
The push refers to repository [docker.io/siddharth67/solar-system]
6bb3b914256b: Pushed
27ef56b51525: Pushed
cd949f4c979d: Pushed
f37b283f479c: Pushed
d324172c3753: Pushed
617df26c92eb: Pushed
ec438b31218: Pushed
1159613137: digest: sha256:55191c68759f6b36e12b0d3667c1b629d2947b25b297c7e05aed021971c09df5 size: 1997
Cleaning up project directory and file based variables
Job succeeded
Once the job completes successfully, visit your Docker Hub repository (siddharth67/solar-system) to confirm the newly pushed tags.
Further Reading
- GitLab CI/CD Variables Documentation
- Docker CLI Reference:
docker push - Docker Hub Repository Management
Watch Video
Watch video content